Buggy code:
public class StompBrokerRelayMessageHandler extends AbstractBrokerMessageHandler { private final MessageChannel messageChannel ; private String relayHost = "127.0.0.1" ; private int relayPort = 61613 ; private String systemLogin = "guest" ; private String systemPasscode = "guest" ; private Environment environment ; private TcpClient < Message < byte [ ] > , Message < byte [ ] > > tcpClient ; private final Map < String , StompBrokerRelayMessageHandler . StompRelaySession > relaySessions = new ConcurrentHashMap < String , StompBrokerRelayMessageHandler . StompRelaySession > ( ) ; public StompBrokerRelayMessageHandler ( MessageChannel messageChannel , Collection < String > destinationPrefixes ) { } public void setRelayHost ( String relayHost ) { } public String getRelayHost ( ) { } public void setRelayPort ( int relayPort ) { } public int getRelayPort ( ) { } public void setSystemLogin ( String systemLogin ) { } public String getSystemLogin ( ) { } public void setSystemPasscode ( String systemPasscode ) { } public String getSystemPasscode ( ) { } @ Override protected void startInternal ( ) { } @ Override protected void stopInternal ( ) { } @ Override protected void handleMessageInternal ( Message < ? > message ) { } private class StompRelaySession { private final String sessionId ; private volatile StompBrokerRelayMessageHandler . StompConnection stompConnection = new StompBrokerRelayMessageHandler . StompConnection ( ) ; private StompRelaySession ( String sessionId ) { } public String getId ( ) { } public void connect ( final Message < ? > connectMessage ) { } protected Composable < TcpConnection < Message < byte [ ] > , Message < byte [ ] > > > initConnection ( ) { } protected void handleConnectionReady ( TcpConnection < Message < byte [ ] > , Message < byte [ ] > > tcpConn , final Message < ? > connectMessage ) { } protected void connectionClosed ( ) { } private void readStompFrame ( Message < byte [ ] > message ) { if ( logger . isTraceEnabled ( ) ) { <START_BUG> logger . trace ( ( "Reading<seq2seq4repair_space>message<seq2seq4repair_space>" + message ) ) ; <END_BUG> } StompHeaderAccessor headers = StompHeaderAccessor . wrap ( message ) ; if ( ( StompCommand . CONNECTED ) == ( headers . getCommand ( ) ) ) { connected ( headers , this . stompConnection ) ; } headers . setSessionId ( this . sessionId ) ; message = MessageBuilder . withPayloadAndHeaders ( message . getPayload ( ) , headers ) . build ( ) ; sendMessageToClient ( message ) ; } protected void connected ( StompHeaderAccessor headers , StompBrokerRelayMessageHandler . StompConnection stompConnection ) { } private void handleTcpClientFailure ( String message , Throwable ex ) { } protected void disconnected ( String errorMessage ) { } private void sendError ( String errorText ) { } protected void sendMessageToClient ( Message < ? > message ) { } public void forward ( Message < ? > message ) { } private boolean forwardInternal ( TcpConnection < Message < byte [ ] > , Message < byte [ ] > > tcpConnection , Message < ? > message ) { } } private static class StompConnection { private volatile TcpConnection < Message < byte [ ] > , Message < byte [ ] > > connection ; private AtomicReference < TcpConnection < Message < byte [ ] > , Message < byte [ ] > > > readyConnection = new AtomicReference < TcpConnection < Message < byte [ ] > , Message < byte [ ] > > > ( ) ; public void setTcpConnection ( TcpConnection < Message < byte [ ] > , Message < byte [ ] > > connection ) { } public TcpConnection < Message < byte [ ] > , Message < byte [ ] > > getReadyConnection ( ) { } public void setReady ( ) { } public boolean isReady ( ) { } public void setDisconnected ( ) { } @ Override public String toString ( ) { } } private class SystemStompRelaySession extends StompBrokerRelayMessageHandler . StompRelaySession { private static final long HEARTBEAT_RECEIVE_MULTIPLIER = 3 ; private static final long HEARTBEAT_SEND_INTERVAL = 10000 ; private static final long HEARTBEAT_RECEIVE_INTERVAL = 10000 ; public static final String ID = "stompRelaySystemSessionId" ; private final byte [ ] heartbeatPayload = new byte [ ] { '\n' } ; public SystemStompRelaySession ( ) { } public void connect ( ) { } @ Override protected Composable < TcpConnection < Message < byte [ ] > , Message < byte [ ] > > > initConnection ( ) { } @ Override protected void connectionClosed ( ) { } @ Override protected void connected ( StompHeaderAccessor headers , final StompBrokerRelayMessageHandler . StompConnection stompConnection ) { } @ Override protected void sendMessageToClient ( Message < ? > message ) { } } }

Fix:
logger . trace ( ( ( ( "Reading<seq2seq4repair_space>message<seq2seq4repair_space>for<seq2seq4repair_space>sessionId=" + ( sessionId ) ) + ",<seq2seq4repair_space>" ) + message ) ) ;